Method of applying plastic coatings to flexible strips and the like



June 4, 1946.

- H. A. cook, JR

METHOD OF APPLYING PLASTIC COATINGS TO FLEXIBLE STRIPS AND THE LIKEFiled June 16, 1943 3 Sheets-Sheet 1 TO VACUUM PUMP STEA LINE I .35 7 Mew STEAM LINE I NV TOR.

Arrow une 4,1946. H. A. cook 2,401,550

METHOD OF APPLYING PLASTIC COATINGS T0 FLEXIBLE STRIPS AND THE LIKEFiled June 16, 194:5 SSheet-Sheet 2 NEYS.

ATTOR .June 4, 1946. H. A. COOK, JR

METHOD OF APPLYING PLASTIC COATINGS TO FLEXIBLE STRIPS AND THE LIKE 5Sheets-Sheet 3 Filed June 16, 1943 INVZ'ENTOR.

I r 1 ATTORNEVYS.

, chloride,

7 Patented June 4, 1946 METHOD OF A PP'LYING COATINGS T FLEXIBLE STRIPSAND THE LIKE net-om Alton Cook, Jr.. Auburn; N. 1., asalgnor to AuburnButton Works, Inc., Auburn, N. Y.,

a corporation of New York Application June 1c, 1943, sem No. 491,078

2 Claims.

I This invention appertains to an improved method of applying plasticcoatings to flexible strips, webs, tapes, and other similar articles andpea. In the methods and machines heretofore employed in applying plasticcoatings to articles of the aforementioned charac er, considerabledifficulty has been met in obtaining a firm adhesion between the plasticcoating and the base material onto which it is applied, and in addition,it has been practically impossible to apply a coating of uniformthickness, particularly where the coating completely surrounds the basematerial. These problems are of considerable importance in theapplication ofdecorative and/or protective coatings to articles ofwearing apparel, such as belts, braces (suspenders), bands, and thelike, which are of greater transverse width than thickness, with theresult that the plastic coating is not equally distributed about thearticle by reason of the lack of pressure balonce on 'the plastic as itextrusion die.

Still another serious problem presented by the conventional plasticcoating machines is the tendency of the plastic material to deteriorateor decompose by bacmng or piling up in bends or turns through which theplastic is directed through the extrusion machine and die, with theconsequent formation of dead spots." This problem is especiallytroublesome in those machines which are characterized by a cross-feed,hat is, where the plastic makes substantially a 90 turn in the extrusionmachine itself, or where the plastic is fed onto an article which ismovin transversely to the direction of flow of the plustic." Some of theplastics, particularly vinyl decompose rather rapidly if allowed tostand or pile up in the coating machine or die. oven .for a few minutes,and when decompositlon has taken place, the plastic becomes dark incolorlor streaked, with consequent darkening or streamng or any freshplastic which may be through the machine adjacent to the decomposed deadspots. Obviously, this produces a very inferior-and unsightly coating,wholly unfit for decorative purposes in the case of articles of neapparel.

With the foregoing principal dimculties in view, among many others notspecifically mentioned. I have provided a new and improved method whichserves to preliminarily remove moisture and air from the interstices andindentations of the or base material to be coated. with plastic, asobtained by preheating the base matepasses through the usual rial,followed by the application of vacuum to the material before the plasticcoating is applied thereto. These steps, together with a progressivelyincreasing application of pressure onto the plastic coating after thecoating is applied to the base material, as obtained by a taperedfinishing die, insure the positive forcing of the plastic into the basematerial, in the case of woven fabric, and in any case, consequent firmadhesion between the base material and the plastic, all without theproduction of air bubbles or air pockets which are so commonly presentin such plastic coated articles.

Another object of my invention is the provision of an improved methodfor producin a "streamlined flow of plastic onto the base material to becoated, and for balancing the pressure throughout the plastic streamjust before it is applied onto the base material, thereby permitting anexceedingly close regulation of the flow of plastic, with consequentapplication of the plastic in uniform thickness about all sides of thebase material. With regard to the streamlining of the plastic flow, thisalso serves the advantage of reducing resistance to flow and substantialelimination of dead spots and consequent decomposition of the plastic.

A further object of my invention is to facilitate the feed of normallyflat strips. webs, belts and the like, of flexible material, byinitially curling the material transversely, preferably after theremoval of moisture and air therefrom as previously mentioned, to enablethe same to be passed into an extrusion die without substantialinterference with the flow of the plastic through the die. Bycurlingthe. base material, wider strips or webs can be successfullyaccommodated than would otherwise be possible with an extrusion die ofgiven dimensions, and without weakening the die or other forming head.

Ancillary to the aforementioned object, my invention additionallycontemplates the provision of an ironing or forming die which flattensand smooths out the initially curled strip material, and thereafterguides it in a straight path which is substantially parallel with theflow of the plastic coating material which is to be ultimately apllliedthereto.

A still further object of my invention is to provide an extrusion die orforming head which is so constructed as to produce a substantiallyselfcleaning action upon the base material to be coated should anyplastic back up into the guides, and also so constructed as to minimizethe back ing up of the plastic material.

size tothe ehtr Other and further objects and advantages of theinvention will be hereinafter described, and the novel features thereofdefined by the appended claims;

In the accompanying drawings;

Figure 1 is a view in vertical section through an extrusion die orforming head constructed according to-my invention,- the same beingshown asapplied to a conventional plastic extrusion machinevof thecylinder and feed-screw type, as in carrying out my improved method ofapplying plastic coatings to flexible strips and the like;

Figure 2 is a sectional view taken on the line 2-2 of Figure 1,transversely to the section of Figure l;

Figure 3 is a sectional view taken on the line 3-3 of Figure 2, andshowing on a somewhat enlarged scale, the details of the streamlinedplastic passages through the extrusion die or forming head, togetherwith the ironing and guiding die and the finishing die, with theirassociated heating chambers; v

Figure 4 is a horizontal sectional view taken on the line 4-4 of Figure2;

Figure 5 is a sectional view taken on the line 6-5 of Figure l, toillustrate the uncurling or the initially curled strip material as itenters the ironing and guiding die;

Figure 6 is a sectional view taken on the line 6-8' of Figures 1 andrespectively, near the forward end of the ironing die,

Figure l is a sectional view taken on the line 1-1 of Figure 1, showingthe strip curling guide which initially imparts a transverse curl to thestrip material before it passes intothe extrusion die or forming head;and

Figure 8 is a perspective detail view of the backstop shoe or plug whichcooperates with the ironing or guiding die in reopening and entering thestrip material into the ironing die, and otherwise prevents the plasticfrom backing up into the strip entering end of the forming head.

Like reference characters designate corresponding parts in the severalfigures of the ,drawins t wherein i designates, in fragmentary form. the

" discharge end of a conventional extrusion machine which may be or anysuitable construction. As illustrated in Figure 1 of the drawings,

said extrusion machine includes the usual plastic feeding cylinder 2through which the plastic is fed axially by the usual screw 3. Thedischarge end of the cylinder 2 is preferably threaded .at

l to receive a correspondingly threaded end 5 of a tubular shellsforming part of an extrusion die or forming head.

As will be best seen irom Figure 1 of the drawings, the end or the shell8 which is threadedly connected to the cylinder 2 is longitudinallybored to provide a belied or tapered chamber i through which the ptic"material enters the i die or for: rhead from the feed the plasticpassing 4 i tcthefeed-screwliscentrallyboredand threaded, as at It, toreceive a correspondingly threaded end on a tapered point I: whichprojects into the belledbore or chamber I, as willbe best understoodfrom reference to Figure 1 of the drawings. This tapered point it servesto divide axially through thechamber I, and to streamline the plastic asit approaches the spider l0 where it enters into the spaced passages lllathe-latter. [The webs -l l-' between the passages I l are preferablybevelled or tapered towards .each passage at the plastic entering endsof the latter, to aid insmoothly directing the plastic into the passagesthrough the spider.

Positioned forwardly of the spider II in' the bore 8 is a combinedironing and guiding die I4 directly forwardly of screw 3. At forward endof the tapered chamber'fl, the t shell-8 is rowess with an in teriorular sheer El, beyond which the shell 1; cylinwlly to a continuouslyuniform w iorwerri end of the cheli. as indicated at t. I I

Mounted-in bore ii and abutt against the shoulder is su cides it whichis presided with a-plty of ii extending In hwushthe spider, saidpassages cquidistently from other about the central axis of the spider,and. being located in outer H 1' spaced relati' to said trei ems, nearthe outer which is made up of an outer shell or bell-piece it,preferably cored out'at ll to provide a steam chamber, and an innersplit .dle I'linwardly spaced from the outer hell I! to form an annularlastic passage 18. The split die i1 is preferably pinned together andscrewed into the end of the spider lb opposite to the tapered point It,which opposite end is threaded as at it.

As will be understood from reference to I8 formed between the outershell-or bell-piece It and the innor die or guide i1 receives theplastic material as it passes through the passages ii in the spider l0,and continues the streamwof the plasti flow. Due to the tapering of theplastic 5 es and chambers, the cross section of the c streamprogressively reduces as the plastic advances towards the forward head.Inthis connection, outer bell l5 and the inner die or quite importantfrom streamlining effect upon the plastic material. and also from thestandpoint of balancing the pressure of the plastic throughout thestream. To the latter end, the forward end of the annular passage i8takes the form of a straight-away, as at 28, to allow the pressure tobecome equal all around the plastic stream before it leaves thispassage.

At the forward end elite of the tubular shell an axial passage 22extending rearward end of this Passage 2!. form an annular shoulder, asat 23, which lies the discharsecndof the 20 in the combinedironstraight-awa passage um shoulder coning and guiding die l4.- Thus,tributes to the balancing of,

the plastic pres the and by virtue of the t which is disposed iorwtheuow' of the e htly in the straight-away pgo 2% until pressure on theplastic has an o i to become perfectly balanced absut the entire plasticstream. w s; the pp from the belied end 28 or the go it, into a portionof-the i go it which has a l tap ss indicated at 26. end-the tapered onis it is arm. as indim at 25.

ction of the i" more iZully ap I of th terial is use the p er: 22 justdescribed h pear.

Surrou the vii -11w die as is a end of the forming the shaping of thethestandpoint of the plastic erethrough. Theis belied out to which ispreferably milled out or cored out at 21 and closed at its forward end ba sealing ri 18 to form a steam chamber. An end plate 29, likewisepreferably cored out as'at 30 to provide an additional steam chamber,abuts against the outer end oil-the collar 26 which is provided at itsrearward end witha'shoulder 3| abutting against a corresponding shoulder32 on the finishing die 2!. Bolts 33, passing through the end plate 29and threadedly received in the outer end of the tubular shell 6, serveto clamp the end plate 29 snugly against the collar 26 and finishing die2!, this clamping action also serving to firmly secure the ironing ,dieand guide M and the spider I in their assembled relation as previouslydescribed. Keys 33' and 33 may be provided to maintain accurate registryof the die parts when assembled, as shown in Figure 4.

In order to more eflectively heat the extrusion die or forming head,should additional heat other than is afforded by the steam chambers it,2?

and it respectively, be required, the tubular shell may be provided withan outer collar or steam jacket Kit, which is suitably cored out toprovide additional steam chambers it having communication with the steamlines 36. To facilitate the application of the steam jacket 34 onto thetubular shell 6, the forward end of the shell is preferably threaded, asat 37, for cooperation with the internally threaded bore of the steamjacket, thus permitting the steam jacket to be readily removed at will.

Having describedthe general features of the extrusion die or forminghead, with particular regard for the flow of plastic therethrough, thereremains to be described thefeed of the article or base material to becoated with the plastic. As will be best seen from reference to Figure 1of the drawings, the article or base material comprises, for thepurposes of this illustration, 2. flexible strip or web of woven fabric,butit is to be understood that my invention is not' limited thereto.Likewise, 'while the strip has been shown in a'form which is rectangularin outline and considerably wider than it is thick, I do not im tend tobe limited to the particular dimensions or reaches the inner end of thetube, even though some air may enter past the gasket or seal II at theouter end of the tube. The inner end of the tube It fits into the upperend of a nipple 43, which may be firmly clamped thereto by the clampingbolts 44, best seen in Figure 2.

Disposed in the upper end of the nipple 43 at the bottom of the vacuumtube 40 is a form or curling die 45 through which the strip 38 passes,and by means of which the strip is curled from a normally flat form intoa generally V- shaped or tubular form, as best shown in Figure 7' ,7.Suitable gaskets or other seals (not shown) may be disposed respectivelyabove and below the form 45 to prevent air from being drawn into thevacuum tube at the Joint between the vacuum tube and the nipple as.

The lower end of the nipple I3- is threadedly received in an opening itprovided, therefor in the wall of the tubular shell 6. From the nipple63 projects downwardly a hollow bolt M concentrio with the axis of thenipple, said hollow bolt fitting in a bore through the wall oi. thetubular shell 6, extending at an angle of approximately 32 from thevertical. Coextensive with the bore through the hollow bolt 47, andforming a contlnuation thereof, is another bore 48 formed in shapeillustrated in the drawings, since other articles of other sizes andshapes may be similarly coated with plastic by suitable changes in theproportions and shapes of the parts of the extrusion die or forminghead.

With the foregoing brief introduction as to the character of thematerial or article to, be coated with plastic, it will be understoodthat the flexible strip material, designated 38, is fed from a suitablesource, not shown, and preferably passes between opposed banks ofinfra-red ray ps, diagrammatically illustrated at 38, 39, by means ofwhich the strip is pre-heate'd and thoroughly dried outto remove anymoisture which may be present therein. After this preheating andmoisture-removing operation, 'the strip the solidweb of the spider i0.between an adjacent pair of plastic passages H. Thus, the flexible strip18, after passing through the form or die as, continiles in itstransversely curled or tubular ,form through the hollow bolt Ill and thebore #8, beyond which. it comesinto engagement with the rearward end ofthe split ironing die or gulde ll. This end of the ironing die or guideii is so shaped as'to cause the'curled strip 88 to be opened up and fedin a restored fiat condltion through a passage 49 corresponding in shapeto the normally flat shape of the strip and extending longitudinallythrough the die H. The restoration of the flat shape of the strip 38 isaided by the use of a special backstop shoe or plug 50, having a pin biprojecting from its rearward side into a corresponding opening 52 formedin the tapered point it. The forward end of the shoe, at its lower side,closely fits the rear end of the lower half of the split die H, asindicated at 53, whereas the upper portion of the am e is spaced fromthe rear end of the upper porl ion oi the split die I], as indicated atH, to permit the strip 33 to pass therebetween and enter the passage 9through the die l1. As the strip then 7 forward end. of the passage 48projects slightly passes into a vacuum tube I, which may have"- which ispresent in the indentations or interstic'es of the strip 88. By reasonof the connection of the manifold 42 to the tube ll at intervals alongthe length of the latter, a relatively highvacuum will be obtained bythe time the strip into the belied mouth 23 of the finishing die 2|. atwhich point the plastic material flowing through the straight-awaypassage 20 of the die H is evenly applied all around the strip. Byreason of the balancing 01"the pressure of the plastic before it isapplied onto the strip, as previously explained, the uniformity ofapplication of the plastic coating is closely regulated and accuratelymaintained.

Now as the strip with the plastic coating thereon advances through thefinishing die ll, the tapering of the passage along the part designated24 causes the plastic to penetrate the strip. in

the case of woven fabric, or otherwise all in irregularities orindentations in the-strip and produce a nrm bond between the plasticcoating and the BJOLBBO understood that the feed of the strip isobtained in any suitable manner. as by exerting a pull thereon from theforward side of the extrusion die or forming head with the aid of apulley which is preferably driven by a variable speed motor.

By carefultemperature control of the sections of the die or forminghead, and by synchronizing the speed of the plastic machine and thespeed ofthe strip to be covered, the'desired plastic coating applicationcan be perfectly regulated. It may also be mentioned in this connectionthat, if desired, the heat applied to the finishing die by the steamchamber 21. may be in the nature of a superheat to aid in the productionof a firm bond between the plastic and the strip to be coat- 9 ed as thestrip passes through the tapered portion of the finishing die. By reasonof the preheating of the strip by means of the infra red forming headare not chilled by the subsequent contact of the strip therewith. Thisalso contributes tothe improved quality of the finished product. f

It will be understood fromthe foregoing that by removal of the end plate20; after removal of theclamping bolts'fl, the spider ll. ironingandguidingdielkandtheiinishingdielimay all be removed fromthe tubularshell t for the purposes of cleaning the same when the occasion sorequires, or to permit the substitution at other dies of suitable sizeand shape to conform 'tothediiferentsizesandshapesofartlclestobecoatedwith plastic. Also, by disconnecting theextrusiondieorformingheadasaimitfromthecylinderfoftheextrudingmachinaasbyum screwing the head therefrom,convenient access.

is given .to the tapered point is to permitthelatter to thereafter beunscrewed and removed from the belied or tapered chamber 1. This removalof the tapered point It, along with the backstop shoe or plug ll,aitords'convenient accesste the interior 0,! theforniing headforthe ofpermitting the flexible strip 38 to be threaded through the guides anddie parts in ad= aneeofthepdintofentrdncedi the stripinte lllitironingdieor guide ill.

of advancement of the strip.

.Byreasonotthecloseregulationorhalancing 'or'the pressure and ilow ofplastic at the approach to the forming die, it is possible by thepractice of my invention to ilow onto the strip both thin and heavysections of the plastic coating to form fancy grooves and edgings whichenhance the attractiveness of the finished product. Also, my inventionmakes pomble the use of delicate shades of plastic under long continuousrims.

1 without any likelihood of decomposition ot the plastic. and consequentdarkening and streaking of the final coating which has heretofore beenso evident in plastic coated articles of this chatacter. It is to beunderstood. or course. that while plastics of the vinyl chloride typemay be effectively used with my invention-various other plastics may beemployed in lieu thereof with equally sood resu ts.

Likewise, while the specific details have been so herein shown anddescribed. my invention is not confined thereto as changes andalterations may be made without departing from the'spirlt thereof asdefined by the appended claims.

I claim:

1. The method of applying plastic normally fiat flexible strips and thelike, which comprises transversely curling the strip preliminary tocoating the same, flowing a tubular stream of plastic in a directiongenerallyaxially of said taming lastic at such ray lamps 30, the partsof the extrusion die or stream while mam the p 3 the curled stripbetween the plastic streams from a point exteriorly of the path of "theplastic to a point interiorly or the same. recombining the spacedplastic streams to encompass the strip and advancing the strip'in a di-'40 rection generallyparallel and coaxial with the r flow or therecombined plastic stream while reflattening andironing out thejcurled,strip. thereafter depositing the plastic onto t he strip inthe form of acoating, progressively compressing the plastic coating about the stripduring a substantiallyprclonged period of advancement of the strip, andthereafter smoothing and shaping theplastictothedesiredshapeandthickness during ,a further substantiallyprolonged period 2."lhe method as v the normally flat p m a substanttubular to ins the same between the a. plastic streams.-

names a. Ja.

